Method for manufacturing cooling members for cooling systems of metallurgical furnaces

ABSTRACT

A method of preventing carbonization of metal pipes during the manufacturing of cooling members for metallurgical furnaces, according to which steel pipes for passing cooling liquid are coated externally with a refractory material and inserted into a mold after which molten iron maintained at a temperature range of from 1,180* to 1,250*C is poured into the mold.

United States Patent [191 Andoniev et al.

[ METHOD FOR MANUFACTURING COOLING MEMBERS FOR COOLING SYSTEMS OF METALLURGICAL FURNACES [76] Inventors: Sergei Mikhailovich Andoniev,

prospekt Pravdy, 5, kv. 60, Kharkov; Nikolai Nikitovich Alexandrov, Sharikopodshipnikovskaya, 2, kv. 147, Moscow; Nikolai Ivanovich Klochnev, Sharikopodshipnikovskaya, 2, kv. 190, Moscow; Evgeny Vladimirovich Kovalevich, Frunzenskaya naberezhnaya, 24, kv. 38, Moscow; Gennady Alexandrovich Kudinov, prospekt Pravdy, 5, kv. 202, Kharkov; Dorina Borisovna Kutsykovich, prospekt Lenina, 39, kv. 54, Kharkov; Vasily Ivanovich Kulikov, Novorosiiskaya, 9, korpus l, kv. 9, Moscow; Oleg Vladimirovich Filipiev, prospekt Pravady, 5, kv. 41, Kharkov, all of USSR.

[22] Filed: Aug. 17, 1972 [21] Appl. No.: 281,533

Related U.S. Application Data [63] Continuation of Ser. No. 77,023, Sept. 30, 1970,

abandoned.

[52] U.S. Cl 164/100, 106/3827, l17/5.3

[111 3,822,736 [451 Jul 9,1974

[51] Int. Cl B22d 19/00 [58] Field of Search 164/100, 101; 266/32, 43; 106/382, 38.27, 38.3, 38.35; 1l7/5.1, 5.3

Making, Shaping and Treating Of Steel, United States Steel, 1964, TN 730 C16 1964C.3, p. 1018.

Primary Examiner l. Spencer Overholser Assistant ExaminerJohn S. Brown Attorney, Agent, or Firm-Holman & Stern [5 7 ABSTRACT A method of preventing carbonization of metal pipes during the manufacturing of cooling members for metallurgical furnaces, according to which steel pipes for passing cooling liquid are coated externally with a refractory material and inserted into a mold after which molten iron maintained at a temperature range of from l,180 to 1,250C is poured into the mold.

2 Claims, N0 Drawings METHOD FOR MANUFACTURING COOLING MEMBERS FOR COOLING SYSTEMS OF METALLURGICAL FURNACES This is a continuation, of application Ser. No. 77,023, filed Sept. 30, 1970 and now abandoned.

BACKGROUND OF THE INVENTION The present invention relates to metallurgy, and more particularly to methods of manufacturing cooling members for cooling systems of metallurgical furnaces.

The jacket of metallurgical furnaces is cooled by using cooling member which are essentially cast-iron plates having steel pipes built-in for allowing passage of a coolant.

In accordance with the prior-art methods, when manufacturing cooling members, steel pipes are laid in foundry molds without using protective coatings, and molten iron is poured into the mold with no temperature control.

The disadvantages of these methods consist in that when the molten iron is poured into the mold, the steel pipes are carbonized as a result of diffusion of carbon from the molten iron into steel. Under these circumstances, the higher the temperature of the molten iron, the faster will be the speed of diffusion and depth of the diffusion layer. Carbonization of the steel pipes results in a marked decrease of their mechanical strength and in a complete loss of plastic properties. As a result, temperature stresses are set up in the cooling members, causing the plates to deform so that cracks are developed therein. When such cooling members are in operation, the walls of the steel pipes are liable to crack with the result that the coolant is leaked therefrom. Thus, the cooling members are prematurely damaged.

Known in the prior art is also a method for manufacturing reinforced parts, consisting in pouring molten metal into a reinforcing structure coated with a protective paste, for example, minimum (cf. the book of N.N. Smeliakov, entitled Reinforced castings, Metallurgizdat, USSR; 1958, pages 33, 52-54).

The use of minimum (red-lead) as a protective coating for steel pipes when manufacturing cooling members therefrom, to some measure allows their protective against corrosion, but not against carbonization.

SUMMARY OF THE INVENTlON An object of the present invention is to prevent the external surface of steel pipes from carbonization when manufacturing cooling members therefrom, and to thus increase the service life of these members.

These objects are achieved by using a method for manufacturing cooling members for metallurgical furnaces. preferably blast furnaces, featuring pouring molten metal into molds, in which steel pipes are laid to allow the passage of a coolant. ln conformity with the invention, prior to pouring the molten iron, the external surface of the pipes is'coated with a refractory material protecting them against carbonization, and the temperature of iron being poured is maintained within a range from l,l80 to l,250C.

DETAlLED DESCRIPTION OF THE INVENTION The present invention will become evident from the following description.

The external surface of the pipes is coated with a refractory material which may contain quartz sand, refractory clay, water glass, and water.

The above constituents should be contained in the refractory material in the following proportions (in wt. percent): quartz sand, 72; refractory clay, 20; water glass, 8; and, additionally, water, in an anount as required for obtaining the density of a mix within a range from 1.4 to 1.6 g/cm.

Prior to coating with the protective material, the external surface of the pipes should be cleaned and coated with a paint containing (in wt. percent): aluminum powder, 20; water glass, 8; and water, 72.

The nature of the present invention will become more fully apparent from a consideration of the following description of an exemplary embodiment thereof.

Then the cleaned surface is coated with a paint conataining (in wt. percent):

aluminium powder 20, water glass 8, water 72.

Afterwards, the painted pipes are to dried.

To protect the external surface of pipes against carbonization, a refractory material is prepared containing (in wt. percent): quartz sand, 72; refractory clay, 20; water glass, 8; and, additionally, water, the amount of which is calculated to ensure density of a mix within a range from L4 to 1.6 g/cm The mix thus prepared is applied to the external surface of the pipes and, dried, which the pipes are lain a mold for manufacturing a cooling member and poured with molten iron which is heated up to a temperature of 1,l to l,200C.

Owing to the fact that the coefficient of diffusion of carbon from molten iron into steel is bound to markedly increase as the temperature rises, the temperature of molten iron being poured should not exceed l,250C. lt is considered desirable that this temperature be nearer l,l80C, i.e., the lower limit.

The refractory material, intended to protect the cleaned external surface of pipes against carbonization, may be applied to the cleaned external surface of the pipes without resorting to their preliminary coating with a paint.

As has been demonstrated by testing, the service life of the cooling member manufactured according to the thusly described method was found to be longer than that obtained with the existing methods, the pipes remaining completely free from carbonization and preserving their original mechanical strength.

Such cooling members can be employed both in the water and evaporative cooling systems, not only in blast furnace, but also in shaft furnaces.

What we claim is:

l. A method of preventing carbonization of metal pipes during the manufacturing of cooling members for cooling systems of metallurgical furnaces comprising the steps of coating the outer surface of pipes to be used for cooling with a thin layer of refractory material; positioning the coated pipes in a mold; and pouring molten iron maintained at a temperature range of from l,l80 to 2,25()C into the mold to form the cooling members, the pipes being free of carbonization due to the low temperature of pouring and the protective refractory material, said refractory material consisting essentially of 72 percent by weight of quartz sand. percent by weight of refractory clay, 8 percent by weight of water glass and water in the amount necessary for obtaining a mixture the density of which is within a range from 1.4 to L6 g/cm.

2. A method of preventing carbonization of metal pipes during the manufacturing of cooling members for cooling systems of metallurgical furnaces comprising the steps of cleaning and coating the outer surface of pipes to be used for cooling with a paint consisting essentially of 20 percent by weight of aluminum powder, 8 percent by weight of water glass and 72 percent by weight of water; coating the outer surface of the pipes with a thin layer of refractory material; positioning the coated pipes in a mold; and pouring molten iron maintained at a temperature range of from l,l to l,250C into the mold to form the cooling members, the pipes being free of carbonization due to the low temperature of pouring and the protective refractory material,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3'822'736 Dated ly 9, 1974 Invent0r(s) SERGEI MIKHAILOVICH ANDONIEV et a1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 4, "ZZSO C" should be 1250 0 Signed and sealed this 8th day of pril 1575.

(SEAL) Attest:

- C. I-LARSE'IALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks i FORM PO-1050 (10-69) I USCOMM-DC 60376-1 69 U 5. GOVERNMENT PRINTING QFFlCE 1 I969 0-365-334 

2. A method of preventing carbonization of metal pipes during the manufacturing of cooling members for cooling systems of metallurgical furnaces comprising the steps of cleaning and coating the outer surface of pipes to be used for cooling with a paint consisting essentially of 20 percent by weight of aluminum powder, 8 percent by weight of water glass and 72 percent by weight of water; coating the outer surface of the pipes with a thin layer of refractory material; positioning the coated pipes in a mold; and pouring molten iron maintained at a temperature range of from 1,180* to 1,250*C into the mold to form the cooling members, the pipes being free of carbonization due to the low temperature of pouring and the protective refractory material. 